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STRATEGIES TO INCREASE THE OUTPUT OF INTENSIVE BEEF PRODUCTION
Introduction
Although a considerable amount of effort has been made to improve beef production efficiency, few studies have taken into account improvements in terms of quality and quantity of beef carcass and meat, with due consideration given to consumer demand-perception, economic, environment and animal welfare consequences. Although beef carcass and meat quality is a complex and dynamic issue, involving the total chain from farm to fork with a multitude of interacting aspects related to producers, slaughtering companies, and wholesalers to retailers, and consumers, it is important to improve carcass and also meat quality characteristics, leading to products with an added value, and to face the large and competitive meat industries of Argentina, Brazil and USA (Van Trijp and Steenkamp, 2005; Gellynck et al., 2006).
Meat quality characteristics are classified into sensorial (associated with colour, flavour, juiciness), nutritional (associated with crude protein content, fat content, amino acids profile, fatty acids profile, vitamins), food safety (associated with microbial pathogens like Escherichia coli O157: H7 and Listeria monocytogenes, and food additives, chemical residues, and products of food biotechnology or genetically modified organisms), and technological categories (associated with tenderness, water holding capacity, pH, moisture). In general, the meat quality information reaches the consumer in the form of quality cues, which are defined by Steenkamp (1997) as informational stimuli that, according to the consumer, say something about the product. Cues can be intrinsic and extrinsic. Intrinsic cues are related to physical aspects of the meat (cut, colour, intramuscular fat content, tenderness, flavour, juiciness), whereas extrinsic cues are related to non-physical aspects of the product (price, origin, stamp of quality, production system and nutritional information). These cues are categorised and integrated for the consumer to infer the quality attributes of meat (Bernués et al., 2003). Additionally in Spain carcass quality characteristics are mainly defined by the backfat (fat cover), and conformation, according to the EU classification system into 1.2.3.4.5 (EU Regulation nº 1208/81) and into (S)EUROP categories (EU Regulation nº 1208/81, 1026/91), respectively. Also hot carcass weight, ultimate meat pH, and extreme bruises are used to specify the value-based marketing of carcass (Sañudo and Campo, 1997). These value-based marketing of carcass involves: 1) payment of incentive to producers capable of supplying animals that meet specific market requirements, and 2) high discounts (around 20 to 30%) when carcass presents bruises, has lower conformation and backfat, or has a high ultimate pH.
Until the present, feeding strategies have been the management factor most actively studied to increase quality of carcass and meat during the finishing phase, leading to products with an added value in this more saturated food market. The latter includes uptake and incorporation of specific feeding components that contribute to lipid content and composition in relation to nutritional value (Wood and Enser, 1997), or influences on technological quality and storage life (Sheard et al., 2004). Additionally genetic breed selection (Keane, 1994; Serra et al., 2004; 2008), gender type selection (Sueiro et al., 1994; Fiems et al., 2003), modifying the age of slaughter (Shackelford et al., 1994) or final body weight (Colomer-Rocher et al., 1980; Sánchez et al., 1997), management production practices (Knight et al., 1999a; 1999b; Realini et al., 2004), and pre-slaughter management (Warriss, 1990) factors have been studied to increase carcass and meat quality. Furthermore, it is possible to increase meat quality through selection methods for raw meat, processing technologies, packaging and distribution systems, delivering “easy to handle”, “ready to cook” or “ready to eat”. At the processing stage, beef meat quality (specially, nutritional quality) can also be increased by reducing the levels of food ingredients and additives with proven negative impacts on human health, and by adding health promoting ingredients, such as micronutrients, probiotics, and other functional food ingredients. Each link in the distribution chain from farm through slaughterhouse to retailer is important in order to improve the carcass and meat quality.
Enhancing carcass and meat quality by modifying the animal management practices
Recently, the Spanish beef industry has reported an increase in the incidence of meat with high ultimate pH. Changes in the pH during the post-mortem period negatively influence the intrinsic characteristics of the meat (Mounier et al., 2006), especially qualities most appreciated by the consumers, e.g. tenderness, juiciness and flavour. De facto, meat with high ultimate pH presents a dark red colour (Bartos et al., 1993), greater water holding capacity (Apple et al., 2005), and poor palatability (Viljoen et al., 2002). From a microbiological point of view, the meat with high ultimate pH has a more rapid growth of microorganisms to unacceptable levels with the development of off-odours, and often slime formation (Pipek et al., 2003; Mach et al., 2007). These changes in the pH reduce the value of the carcasses, representing a serious economic problem in the meat industry. Frequently, the discounts associated with meat ultimate pH greater than 6.0 are around 150 € per animal (Data not published, IRTA 2008).
After exsanguination, as soon as blood flow ceases, muscle cells are subjected to hypoxia and soon after to hyperosmotic conditions. The cell responses to these stresses are multiple. With the development of hypoxic conditions after bleeding, the first modification is very likely to be a rapid decline of the pH as a result of lactic acid produced from anaerobic glycolysis (Figure 1). This feature is probably the major cause of the amplitude of the pH decline always observed upon the 30 to 60 min post-mortem. In fact, it is stated that the causes of muscle acidification are multiple. When phosphocreatine stores are exhausted, the required energy is mainly produced through the anaerobic degradation of glycogen by glycolysis.
Glycogen is a branched polysaccharide of α-D-Glucose unit. In beef, muscle glycogen concentration ranges between 75 and 120mol/g (Immonen et al., 2000), and depends on the net result of utilization and production by muscle (Immonen et al., 2000). The average rate of glycogen break down was reported to be 10 to 11mol/g/h (range 5 to 24) in young bulls severely stressed by co-mingling or adrenaline administration (Tarrant and Lacourt, 1984), whereas the rate of repletion is slow, 1.6mol/g/h (McVeigh and Tarrant, 1983). Not all muscle glycogen is synthesized from glucose originating directly from liver glycogen; some glucose absorbed from the alimentary tract may serve directly in muscle glycogen synthesis.
Figure 1. A schematic representation of the rate of pH decline post-mortem in normal beef meat and in beef meat with high ultimate pH (Warriss, 1990)
About 45mol of glycogen is needed to lower the pH of 1 kg of muscle from 7.2 to 5.5 (Immonen et al., 2000). This equals to 7g/kg of muscle. Warriss (1990) presented a figure on the relationship of ultimate pH to the concentration of glycogen present in the LM at death. Data on the curvilinear dependence consisted of 2,345 observations and revealed that pH decline appears to be limited only below glycogen concentration of 45mol/g. Various authors have reported glycogen concentration at the time of slaughter and the corresponding ultimate pH values. Lahucky et al. (1998) measured glycogen concentration immediately prior to slaughter from control and stressed bulls. The glycogen concentrations were 61 and 33mol/g, producing pH values of 5.66 and 6.70, respectively. Immonen and Poulanne (2000) found that at pH values below 5.75, bovine muscle residual glycogen concentrations varied from 10 to above 80mol/g, showing that pH is a relatively “insensitive” measure for understanding the physiology of muscle (e.g. after physical and physiological stress), since the muscle glycogen in the live animals must be depleted about 70 to 80mol/g without changes in pH.
Presumably, post-mortem glycolysis and muscle pH decline is stopped, under normal carcass chilling conditions, when muscle pH declines to approximately 5.45, and this low pH inhibits the activity of glycolytic enzymes, or when muscle glycogen concentrations are depleted. However, the rate of the pH decline also depends on the efficiency of the glycolytic pathway, and the buffering capacities of muscle cells. The very fast decline of pH immediately after bleeding can probably not only be ascribed to glycolysis and the subsequent accumulation of lactic acid. This was supported by the increase in the level of enzymes involved in the oxidative and the glycolytic pathways within 20 min after slaughter, two pathways providing the energy needed to preserve cells from death and/or setup the program cell death machinery (Jia et al., 2006ab). The findings of Jia et al. (2006ab) further demonstrate that protein synthesis takes place after animal bleeding and prove the intense metabolic activity of post-mortem muscle cells suggested before. Replacement of acidic components (phosphatidylserine) by basic components (phosphatidylcholine and phosphatidylethanolamine) in the intracellular compartment, accompanied by a redistribution of ions, could explain the existence of transient pH stability steps (Ouali et al., 2006), which occurs between 1 and 8 h post-mortem. Additionally, glycogen concentration shows an inherently variable nature dependent on breed, nutritional status of animal, physical exhaustion and psychological pre-slaughter stress, electrical stimulation, and the type of muscle (e. g. oxidative vs. glycolytic). Each muscle fiber type has different biochemical and biophysical characteristics such as oxidative and glycolytic capacities, contraction speed, fiber size, myoglobin, and glycogen concentration (Brandsteteer et al., 1998). Muscle fiber type I has slow-twitch, oxidative metabolic characteristics, and a low glycogen concentration, whereas type II A is a fast oxidative–glycolytic fiber. On the other hand, type IIB has fast-twitch, glycolytic metabolic characteristics, and a high glycogen concentration (Karlsson et al., 1999). Thus, muscles with different fiber type composition have different effects on post-mortem glycogen concentration, and may have a subsequent influence on ultimate meat pH (Ozawa et al., 2000).
As described below, physical exhaustion and psychological pre-slaughter stress of cattle might reduce the glycogen concentration (Immonen and Puolanne, 2000). During pre-slaughter phase animals can be exposed to a range of challenging stimuli including: time, handling and increased human contact, loading and unloading, novel/unfamiliar environments, food and water deprivation, changes in social structure (e. g. through separation and mixing animals from different farms and/or pens), high stocking densities during transportation or at the slaughterhouse, and changes in climatic conditions. In fact, this physical exhaustion and psychological pre-slaughter stress perturb the animal well being (fear, dehydration, fatigue, physical injury), and an adaptive response is activated in an attempt of restore balance (Ferguson and Warner, 2008). Adaptive response can be non-specific, and considerable variability exists between animals not only in their perception of the stressor but also in their coordination of the response (Moberg, 2001). Several intrinsic animal factors (e. g. genetics, sex, age, and physiological state), past experiences, and acquired learning (Moberg, 2001), the type, duration, and intensity of individual pre-slaughter stressors might affect the adaptive response (Ferguson et al., 2001). The activation and regulation of the neuroendocrinal response to fear-eliciting stimuli has been studied extensively by Steckler (2005). The two central integrated processes include the autonomic nervous system and hypothalamic-pituitary-adrenal (HPA) axis. It has been reported that the secretion of catecholamine affects the incidence of high ultimate meat pH as a result of significant changes in energy metabolism including lipolysis, glycogenolysis and gluconeogenesis (Kuchel, 1991).
In fact, the high incidence of ultimate meat pH might be mitigated by the repletion of muscle glycogen concentration. In humans, the rate of muscle glycogen recovery is optimized by consumption of 1.0 g of carbohydrate supplement per kilogram of body weight immediately after cessation of exercise (Ivy et al. 1988), although full recovery within 24 h requires a total intake of 500 g of carbohydrate (Costill et al., 1981). Adding small amounts of protein (0.3 to 0.34 g/kg of body weight) increased the rate of muscle glycogen storage in humans due to the synergistic insulin response produced by the combination of protein and insulin (Zawadzki et al., 1992). In lambs, Chrystall et al. (1981) reported that muscle glycogen slowly replenished after transport and exercise despite denial of food and water. Gardner et al. (2001), feeding cattle with 4 dietary treatments: hay, silage, hay-barley, and hay-maize reported that after the exercise regimen (cattle were trotted at 9 km/h for five 15-min intervals), glycogen concentration repleted in a linear fashion over 72 h in the M. semimenbranosus of the animals fed maize, barley, and silage. In contrast, the M. semitendinosus of these animals was refractory to glycogen repletion over the same period. Both the M. semimenbranosus and M. semitendinosus of the cattle on the hay diet showed no significant repletion following exercise, suggesting a positive linear relationship between glycogen repletion and ME intake.
Great attempts have been made to increase the availability of glucose to ruminants before slaughter, and thus, enhance muscle glycogen synthesis and storage, although results have not always been achieved. Propionate produced by the ruminal fermentation is the main precursor for hepatic glucose production in the ruminant. Therefore, several studies have focused in feeding diets rich in highly fermentable carbohydrate prior to pre-slaughter stress, in order to increase the amount of propionate acid. Additionally, the administration of selective antibiotics, such as monensin, to reduce methane energy losses and to promote increased propionate production, or the use of direct-fed microbial products has been studied. Feeding nutrients in a form that will largely protect them from fermentation without affecting enzymatic degradation lower down the gastrointestinal tract, have also been investigated with the objective to increase the availability of glucose to ruminants (Leek, 1993). Gardner and Pethick (2005) reported that glycerol and propylene glycol mixed in drinking water at the rate of 3.5% and 1.5%, respectively, during 24 h of waiting time at slaughterhouse, were effective in reducing the ultimate pH of cattle about 0.1-pH unit. In addition, Parker et al. (2007) reported that steers orally dosed at 24 and 48 h before slaughter with glycerol (2 g/kg BW) presented greater glucose concentrations that non-supplemented steers, and suggested that elevated blood glucose concentration in the glycerol treated animals may provide a preferential fuel for liver gluconeogenesis. Additionally, although full-feeding cattle on arrival at packing plants is not practical under commercial conditions, Schaefer et al. (1999) suggested that a low rate of supplementation of a concentrate diet would have beneficial effects on tissue catabolism of stressed animals. In fact, Schaefer et al. (1999) stated that modification of the diet for a short period (1 to 2 d) immediately before cattle transport and (or) providing a relatively small amount of a nutrition supplement during waiting time at the slaughterhouse (e.g. ions, and amino acids) offers the potential to improve carcass yield, and reduce meat quality defects.
Additionally, great attempts have been made to decrease the depletion of glucose in ruminants before slaughter through management practices. In fact, the effects of stress factors on muscle glycogen depletion and the consequent incidence of high ultimate meat pH have been well documented (Ferguson et al., 2008). However, there has been little examination of the consequence of the interaction of those pre-slaughter factors (concerned with animal, farm, transport and slaughterhouse) on meat ultimate pH.
In addition to the important incidence of meat with high ultimate pH, the Spanish market today is facing other carcass and meat quality problems. The optimal hot carcass weight (HCW) is between 272 and 340 kg. In addition, the optimal carcass conformation is the “R” category (when profiles on the whole are straight with good muscle development), and the optimal degree of carcass backfat is the “3” category (when carcasses present flesh, with the exception of the round and shoulder, and are covered with fat, with slight deposits of fat in the thoracic cavity). However, in Holstein bulls (70% of total bulls produced in Catalonia), 86.9% of their carcasses are classified as “O” in conformation, and 44.6% of carcasses are classified as “2” in backfat following EU Regulation (Data from Mercabarna Slaughterhouse, 2007). Carcasses from Holstein young bulls clearly present less conformation and backfat than that desired in the Spanish market. For instance, for young Holstein bulls with hot carcass weights < 300 kg, the economic losses between “R” or “O” conformation category are close to 37 € per animal (Mercabarna, 2008). One way to solve these carcass and meat quality problems with Holstein young-bulls could be castration. Castration of bulls increases intramuscular fat content (Knight et al., 1999ab), carcass backfat (Field, 1971; Knight et al., 1999a), which determines carcass final prices, and tenderness (Morgan et al., 1993). The differences between carcass and meat quality of castrated animals and intact bulls are mainly associated with an inhibition of anabolic hormones produced by the testes (Adams et al., 1996). Therefore, Boccard et al. (1979) and Mc Cormick (1992) reported that castrated animals presented lower concentrations of hydroxyproline (the main component of collagen protein) than intact bulls, as a result of the lack of the anabolic effects of testosterone on collagen synthesis. Although these studies have linked bull meat tenderness to greater amounts of connective tissue, the proteolysis may be affected by castration. Morgan et al. (1993) reported an important relationship between enzymes activity at 24 h post-mortem, myofibrillar proteolysis, and meat tenderization in castrated animals. Morgan et al. (1993) reported greater amounts of proteolysis in muscle from castrated animals during the first 7 d post-mortem than in intact bulls, probably as a result of the greater-calpain activity. Probably, proteomic techniques will be a good instrument to enhance the relatively little knowledge of the changes in the total tissue proteome after castration, and during ageing.
On the other hand, as a result of the changes in complex system of growth factors like growth hormone (GH), insulin-like growth factor I (IGF-I), insulin, thyroid hormones and anabolic hormones produced by the testes, castrated animals exhibit lower growth rates and feed efficiencies, and dressing percentages than intact males. Anabolic hormones produced by the testes are responsible for the differential in growth between intact males and castrated animals, as testosterone is a potent muscle growth stimulant that counteracts fat deposition. In addition, while castration can contribute to improvements in beef carcass quality, attention must be given to animal welfare. The LayWel report (Bessei, 2005) reported that most definitions of welfare include physical, physiologic, and psychological/mental aspects. Indicators of poor welfare (decrease growth, body damage and illness, and increase in abnormal behaviour) can be used to assess animal welfare after castration management. Therefore, in order to optimize the animal welfare related to castration, further research (specially in acute and chronic pain and stress) is needed to ensure that castration is a good method to improve the outputs of intensive beef production system.
Enhancing meat quality by feeding animals from different dietary sources
In the food guide pyramid, meat is categorized as a protein food group along with poultry, fish and eggs. Undoubtedly, meat is a major source of food proteins with a high biological value in many countries (Arihara, 2006). Meat is also an excellent source of some valuable nutrients such as minerals and vitamins (Biesalski, 2005). Regrettably, over the last 10-15 years, these positive attributes have often been overshadowed due to the perception that beef contains high amounts of fat, which has been related to some diseases when consumed in excess. Today, it is accepted that both, the amount and the profile of the fatty acids, are risk factors in the development of some diseases. Therefore, it is recommended that people should decrease their intake of saturated fatty acids (less than 10% of the total calories) and trans-fatty acids (less than 1%), increase the intake of unsaturated fatty acids (more than 0.5%), and decrease the omega-6 (n-6) to omega-3 (n-3) ratio fatty acids in the diet to levels 5 to 1 (World Health Organisation (WHO), 2003). More recently, Wijendran and Hayes (2004) have described the importance of providing a ratio of n-6 to n-3 fatty acid close to 6.0 in human diets, but have also emphasized, when contemplating long-term consumptions of fatty acids, that the first consideration should be the absolute amounts of n-6 and n-3 consumed, rather than their ratio.
In that sense, Wijendran and Hayes (2004) recommended 1.7 g/d of α-linolenic acid (ALA) based on the reduction of platelet aggregation in hyperlipidemic subjects when they consumed this ALA amounts daily (Freese et al. 1994).
As consumers are increasingly aware of the relationships between diet and health, particularly in relation to cancer, atherosclerosis and obesity/type 2 diabetes, efforts have been made by the food industry to convert products into a functional food. Functional food is a food similar in appearance to a conventional food, consumed as a part of the usual diet, which contains biologically active components with demonstrated physiological benefits (Food and Agriculture Organization (FAO), 2004). Examples of benefits of functional foods are anticarcinogenicity, antimutagenicity, and antioxidative activity (Arihara, 2006).
The most intensively investigated functional foods are those enriched with n-3 fatty acids (Hasler, 2002). The n-3 fatty acids are predominantly found in fatty fish such as salmon, tuna, sardines and herring (Kris-Etherton et al., 2000; Lee and Lip, 2003). The n-3 fatty acids, especially α-linolenic acid (ALA, cis-9, cis-12, cis-15-18: 3), eicosapentaenoic acid (EPA, cis-5, cis-8, cis-11, cis-14, cis-17-20: 5), and docosahexaenoic acid (DHA, cis-7, cis-10, cis-13, cis-16, cis-19-22: 6) have been reported to exert beneficial effects during growth and development, and prevent and treat cardiovascular diseases, inflammatory and autoimmune disorders, cancer, depression, and psychological stress (Hasler, 2002; Lee and Lip, 2003; Larsson et al., 2004; Logan, 2004).
It is known that intake of n-3 fatty acids is much lower today than at the beginning of the last century due to decrease in fish consumption, and the increase in meat consumption from animals fed with concentrates rich in grains containing n-6 (Mandell et al., 1997; Sanders, 2000). The ratio of n-6 to n-3 fatty acids can be improved by decreasing n-6 consumption, increasing n-3 consumption, or both. As a result of this lack in n-3 fatty acids consumption, there has been a great deal of interest in enriching beef with n-3 fatty acids by modifying the ruminant diets to respond to consumers demands (Scollan et al., 2001, 2003). The main sources of supplementary n-3 fatty acids in ruminant rations are plant oils and oilseeds (mainly linseed oil and whole seed), fish oil, marine algae, and fat supplements (Givens et al., 2000). Fish oil is rich in n-3 fatty acids, specially the long-chain n-3 fatty acids EPA and DHA, but it is not well accepted by the producers, also the concentrations of EPA and DHA are dependent of the species of fish and represents, at most, 25% of fish oil fatty acids, the rest often being rich in saturated fatty acids (Givens et al., 2000). A prudent strategy would be to concentrate these fatty acids prior to ruminal protection. On the other hand, marine algae are not included in ruminant diets because of their high price. Feeding oilseeds to beef is one of the best methods of enhancing the proportion of n-3 fatty acids in meat. Linseed would be a good choice from the consumer point of view, being a source of linolenic acid (56% of the total fatty acids). To enrich beef with n-3 fatty acids, the dietary supply of n-3 fatty acids must escape rumen biohydrogenation (which converts unsaturated fatty acids to saturated fatty acids) before it can be absorbed in the small intestine and deposited in meat. One strategy to avoid rumen biohydrogenation is to feed whole oilseeds, because the seed coat prevents the access of rumen microorganisms to the unsaturated fatty acids (Aldrich et al., 1997). Additionally, a variety of procedures have been explored including the use of heat/chemical treatment of whole/processed oilseeds, rolled or cracked whole oilseeds, chemical treatments of oils to form calcium soups or amides, emulsification/encapsulation of oils with protein and subsequent chemical protection, in order to increase the amount of n-3 fatty acids in tissue (Ashes et al., 2000). Hence, for example, using the later technology, Scollan et al. (2003) showed that a protected plant oil supplement markedly improved the polyunsaturated to saturate ratio (from 0.08 to 0.27) by increased the n-6 to n-3 fatty acids ratio (from 2.75 to 3.59) in beef muscle. However, Choi et al. (2000) and Raes et al. (2004) also increased the n-3 fatty acid content of muscle in late maturing breeds of cattle by feeding forage-based diet supplemented with oils or extruded and crushed linseed rich in ALA, EPA or DHA. It is noteworthy that feeding fresh grass or grass silage compared to concentrates, rich in n-3 and n-6 fatty acids, respectively, also results in greater concentrations of n-3 fatty acids in muscle lipids, both in the triacylglycerol and phospholipids fractions (Nuernberg et al., 2005). Significantly, grass compared to concentrate feeding not only increased n-3 fatty acids muscle phospholipids but also EPA, DPA and DHA (Dannenberger et al., 2004). Studies in Ireland showed that both the proportion of grass in the diet and length of time on grass were important in determining the response in beef fatty acids (Noci et al., 2005).
However, in Europe the demand for functional foods varies remarkably from country to country, on the basis of the alimentary traditions, the enforced legislation, and the different cultural heritage that people have acquired. The opportunities of expansion on the market seem to be quite favourable and the interest of the consumers is rather high, but the diffusion of these products in Spain is slowed down by various obstacles, including certification legislation and prices of purchase ingredients (specially oilseeds).
INPUT OF INTENSIVE BEEF PRODUCTION
The main cost of intensive beef production is the feed cost during the growing and finishing phase (Herd et al., 2004), followed by the cost of buying calves (Departament d’Agricultura, Alimentació i Acció Rural, 2008). Properly managing of feed ingredients and calf purchase is critical to the success of the beef production efficiency. Nowadays, in Catalonia the purchase price of Holstein calves aged between 1 and 3 week averages 170 euros/animal, although in February 2008 it had been reduced by 13.37% compared with August 2006 (Ministerio de Medio Ambiente y Medio Rural y Marino, 2008). This reduction of calf purchase price was similar in France (104 euros/animal in November 2007, 32% less compared with November 2006), Ireland and Germany (82 and 89 euros/animal in November 2007, 14 and 15% less compared with November 2006 respectively). Today calf purchase prices in Catalonia (and Spain) are greater than in other countries as a result of structural deficit of calves. In fact during 2006, around 550,000 animals were imported, mainly from eastern UE-25 countries (Calcedo, 2008). In contrast, the cost of most commonly feed ingredients used in beef diet formulation has increased above to 40.9% since August 2006 to August 2008 (Departament d’Agricultura, Alimentació i Acció Rural, 2008). This recent situation has made producers to look closely for factors such as feed availability and its prices, feed quality, and alternative feeds for beef. During 2008 springtime and summer season cereal and soybeans prices have risen dramatically (Figure 2 and Figure 3). One of the main contributors in rising cereal and soybean prices is the economic growth in many developing countries, which has led to an increase middle-class consumers, generating an increase in food demand.
Table of contents :
CHAPTER I: INTRODUCTION
1. Introduction
2. Description of intensive beef production
2.1. Introduction
2.2. Efficiency of intensive beef production
2.3. Strategies to increase the output of intensive beef production
2.3.1. Introduction
2.3.2. Enhancing carcass and meat quality by modifying the animal management practices
2.3.3. Enhancing meat quality by feeding animals from different dietary sources
2.4. Input of intensive beef production
2.5. Strategies to reduce the inputs into intensive beef production system during the finishing phase
2.5.1. Introduction
2.5.2. Increasing intensive beef production efficiency by increasing feed efficiency
2.5.3. Increasing intensive beef production efficiency by using alternative feed ingredients
3. Summary
4. Literature cited
CHAPTER II: OBJECTIVES
CHAPTER III: ASSOCIATION BETWEEN ANIMAL, TRANSPORTATION, SLAUGHTERHOUSE PRACTICES AND BEEF EXTREME CARCASS BRUISES AND ULTIMATE MEAT pH
Abstract
1. Introduction
2. Materials and Methods
2.1. Data collection
2.2. Measurements and Sample Collection
2.3. Statistical analyses
3. Results and Discussion
4. Implications
5. Literature cited
CHAPTER IV: BURDIZZO PRE-PUBERTAL CASTRATION EFFECTS ON PERFORMANCE, BEHAVIOUR, CARCASS CHARACTERISITICS AND MEAT QUALITY OF YOUNG HOLSTEIN BULLS FED HIGH-CONCENTRATE DIETS
Abstract
1. Introduction
2. Materials and Methods
2.1. Animal, Housing and Treatments
2.2. Measurements and Sample Collection
2.3. Chemical Analyses
2.4. Statistical analyses
3. Results and Discussion
3.1. Intake, and Animal Performance
3.2. Animal Behaviour
3.3. Testes Characteristics
3.4. Carcass and Meat Quality Characteristics
4. Implications
5. Literature cited
CHAPTER V: INCREASING THE AMOUNT OF OMEGA-3 FATTY ACID OF MEAT FROM INTENSIVELY FED YOUNG HOLSTEIN BULLS THROUGH NUTRITION
Abstract
1. Introduction
2. Materials and Methods
2.1. Animal, Housing and Treatments
2.2. Measurements and Sample Collection
2.3. Chemical Analyses
2.4. Statistical analyses
3. Results and Discussion
3.1. Intake, and Animal Performance
3.2. Ruminal Fermentation
3.3. Carcass and Meat Quality Characteristics
3.4. Fatty Acid Composition of the LM
4. Implications
5. Literature cited
CHAPTER VI: EFFECTS OF GLYCERIN SUPPLEMENTATION ON PERFORMANCE AND MEAT QUALITY OF YOUNG HOLSTEIN BULLS FED HIGH-CONCENTRATE DIET
Abstract
1. Introduction
2. Materials and Methods
2.1. Animal, Housing and Treatments
2.2. Measurements and Sample Collection
2.3. Chemical Analyses
2.4. Statistical analyses
3. Results and Discussion
3.1. Intake, and Animal Performance
3.2. Ruminal Fermentation
3.3. Animal Metabolism
3.4. Carcass and Meat Quality Characteristics
4. Implications
5. Literature cited
CHAPTER VII: GENERAL DISCUSSION OF RESULTS
1. Enhancing carcass and meat quality by modifying the animal feeding or management practices
1.1. Enhancing carcass and meat quality by modifying the management practices
1.1.1. Enhancing the carcass and meat quality by reducing the incidence of meat with high ultimate pH and extreme carcass bruising
1.1.2. Enhancing carcass and meat quality by castration
1.2. Enhancing meat quality by feeding animals a concentrate rich whole linseed
2. Reducing the cost of beef production system throughout feeding strategies
3. Literature cited
CHAPTER VIII: FINAL CONCLUSIONS
